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Single atom memory device stores data

A workable atomic memory that uses individual atoms to store information has been developed by physicists for the first time.

“The difference between a one and a zero is represented by a single atom,” says Franz Himpsel of the University of Wisconsin.

Current hard drives use millions of atoms to store each individual bit of information. In contrast, the new system could be used to squeeze millions of times more data on to a disk of comparable size.

This represents a density equivalent to 250 terabits of data per square inch, although only a few dozen bits were actually stored in the demonstration. The atomic memory drive mimics a conventional hard drive, meaning it can be formatted and data could be written to it and read from it.

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Each single silicon atom was added or removed from a block of twenty others using a scanning tunnelling microscope. The microscope was also used to read these “bits” of data. All of the atoms are kept in place using a lattice of dimples created on the surface of a wafer of silicon by evaporating a layer of gold.

Off the mark

Himpsel says it took minutes to write a few hundred bits of information using the microscope. Compared to current speeds, this method “is so far off the mark, it will have a hard time ever making it,” he says.

The team also showed that working with individual atoms is unlikely ever to match the speed of current memory technologies. This is because of the low energies involved at the atomic scale.

“As density increases, your ability to read the memory comes down because you get less and less of a signal,” Himpsel says. But he adds that the system might be suited to storing images or other information that does not have to be perfect.

Self-organising

Other researchers have shown that atoms can be pushed about when cooled to extreme temperatures, potentially providing atomic data storage. But the new atomic drive was operates at room temperature. The atoms were packed tightly together to keep them in place at this higher temperature and the scanning tunnelling microscope was used to pick them up instead of push them around.

Tom Theis, director of physical sciences at IBM’s T.J. Watson Research Center, in New York, told New Scientist&colon; “The scientifically interesting aspect of this research is the emphasis on self-assembly. The grooved alignment structures are naturally self-organising systems.”

Theis adds that one day it may be possible to mimic the memory capabilities of biological systems such as DNA. He adds&colon; “If this happens, it will be partly because scientists like Franz Himpsel have explored the limits of what is possible.”

Researchers at the University of Basel in Switzerland worked with the University of Wisconsin team to develop the atomic memory system.